Analysis on foulants shows that: the elements (except for C, H and O) in foulants formed during evaporating alkaline wheat straw black liquor are Si, Ca , K, Na, Mg and Al; Si and Ca account for about 36% of the weigh...Analysis on foulants shows that: the elements (except for C, H and O) in foulants formed during evaporating alkaline wheat straw black liquor are Si, Ca , K, Na, Mg and Al; Si and Ca account for about 36% of the weight of foulants; The organic ingredients amout to about 20% of the foulant; Rhodesite (Ca,K,Na)8Si16O40·11H2O is the main composition in foulants. The fouling mechanism of wheat black liquor is quite different from that of soft/hard wood black liquor, because the content of Si inside wheat straw black liquor is much more than that of soft/hard wood black liquor. Complex chemical reactions occur when evaporating wheat straw black liquor. The author considers that colloid H2SiO3 plays an important role in the process. The minerals produced by reactions between H2SiO3, with anion charges and positive ions, such as Ca2+, K+, Na+, etc. Further investigation on the process should be done.The fractal theory is used to analyze the fouling geometric texture. The fractal dimension values D of foulants are also calculated.展开更多
A novel vapor-liquid-solid circulating fluidized bed evaporator, meaning for enhancing heat transfer and preventing fouling, is applied to wheat straw black liquor, which is the primary pollutant in China’s papermaki...A novel vapor-liquid-solid circulating fluidized bed evaporator, meaning for enhancing heat transfer and preventing fouling, is applied to wheat straw black liquor, which is the primary pollutant in China’s papermaking industry. It is treated by alkali recovery, in which evaporation is a key process. The experimental results show that the vapor-liquid-solid three-phase boiling heat transfer coefficient is enhanced by 20%～40% than that of vapor-liquid two-phase boiling flow, also, the novel evaporator exhibits an excellent function of fouling prevention.展开更多
文摘Analysis on foulants shows that: the elements (except for C, H and O) in foulants formed during evaporating alkaline wheat straw black liquor are Si, Ca , K, Na, Mg and Al; Si and Ca account for about 36% of the weight of foulants; The organic ingredients amout to about 20% of the foulant; Rhodesite (Ca,K,Na)8Si16O40·11H2O is the main composition in foulants. The fouling mechanism of wheat black liquor is quite different from that of soft/hard wood black liquor, because the content of Si inside wheat straw black liquor is much more than that of soft/hard wood black liquor. Complex chemical reactions occur when evaporating wheat straw black liquor. The author considers that colloid H2SiO3 plays an important role in the process. The minerals produced by reactions between H2SiO3, with anion charges and positive ions, such as Ca2+, K+, Na+, etc. Further investigation on the process should be done.The fractal theory is used to analyze the fouling geometric texture. The fractal dimension values D of foulants are also calculated.
文摘A novel vapor-liquid-solid circulating fluidized bed evaporator, meaning for enhancing heat transfer and preventing fouling, is applied to wheat straw black liquor, which is the primary pollutant in China’s papermaking industry. It is treated by alkali recovery, in which evaporation is a key process. The experimental results show that the vapor-liquid-solid three-phase boiling heat transfer coefficient is enhanced by 20%～40% than that of vapor-liquid two-phase boiling flow, also, the novel evaporator exhibits an excellent function of fouling prevention.
